The theory, fabrication, and performance of monolithic 4 × 4 single-mode fused couplers is reported. The field coupling matrix is derived and used to show that a device having equal coupling between the four fibers may be obtained. The fabrication of such a device is described, and measurements show that the device exhibits excellent coupling uniformity and low excess loss. The wavelength response of a device designed for equal coupling at 1.53 μm is shown between 1.2 and 1.6 μm.
© 1990 Optical Society of America
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